In the operation of internal combustion automotive engines, the length of the pushrods which connect between the rocker arms and the cam shaft has a direct affect on the timing of and wear on the valvetrain and, in turn, on engine performance and longevity, especially in high performance engines. Particularly when engines may be retrofitted with aftermarket cam shafts, rocker arms and valves, the installation of pushrods of a correct length is often critical to achieving full performance of the valvetrain.
Aftermarket pushrods are available in varying lengths and widths, along with pushrod length checking tools. In additional, pushrods are known to include threaded connections to the rocker arms as a means of attaching the pushrod to the rocker arm with the capability to make fine adjustments to the pushrod length via the threaded connection.
A disadvantage of such pushrod assemblies is that the body of the rocker arm must be sufficiently large to accommodate and support the threaded connection which increases the overall weight of such assembly and correspondingly increases the moment of inertia of the rocker arm which, in turn, detracts from valvetrain stability and dynamics. Accordingly, a need exists for an optimized configuration of pushrod adjustment without a negative affect on valvetrain dynamics.